Locking system



May 17, 1949.

Filed June l5, 1946 F. E. SEAMAN LOCKING SYSTEM 3 Sheets-Sheet l SCI, lo I4 |2 le; u

5 73 74 www 2: aa f 3,6 37

Francis ESeomcn.

ATmpA/Eys F. E. 'SEAMAN LOCKING SYSTEM May 17, 1949.

s Smets-sheet s Filed June 15, 1946 UINVENTOR. Francls E. Seaman.

A T TOR/JE YS Patented May 17,1949

UNITED STATES APATENT 'OF-CE Francis Eiseaman, Columbus, Ohio Application June 15, 194e, serial 10.671069 11 Claims.

My invention relates to a locking system. It has to do, more particularly, with a locking system which is especially adaptable to the doors of an automobile, although it is not limited thereto.

One of the objects of my invention is to provide a thoroughly reliable and positive system for locking' a plurality of doors from a central point.

Another object of my invention is to provide such a system which may be applied to the doors of an automobile in such a manner that the system is under the sole control of the driver of the automobile at all times.

Another object of my invention is to provide a locking system of the type indicated which may be set by the driver when the driver and passengers are inside to lock all of the doors, as a safety measure, it being impossible for anyone inside the car to unlock any of the doors, except from a central control point adjacent the drivers position, and it Ibeing impossible for anyone outside the car to open the doors.

Another object of my invention is to provide such a door locking system which may be set by the driver before leaving the car so that all the doors will be locked automatically upon slamming the doors.

Another object of my invention is to provide a locking system of'such a nature that the bolt of the door lock cannot be locked in locking position unless the door is closed, thereby, eliminating danger of damage to the lock mechanism which would occur if the bolt was locked and the door was slammed.

Another object of my invention is to provide such a door locking system which is electro-magnetically operated and is particularly applicable to an automobile, which is provided with means whereby at least one ofthe doors may be mechanically opened in case of failure of the electrical system of the automobile.

Another object of my invention is to provide an electrically operated door locking system which will require current only momentarily during the locking and unlocking operations and, therefore, will consume only a minimum amount of current. Another object of my invention is to provide such a locking system which includes means for signalling to the driver each time the locking mechanism liunctionsproperly to lock or unlock all the doors; and ysignalling-means, which after initially beingllurned on, Awill function constantly to indicate to the driver at a glance whether or not thedoors-are in locked or unlocked condition.

(Cl. l-264) Various other objects will be apparent hereinafter. I

In its preferred form, the locking system which I have devised comprises an electro-magnetic unit which is associated withveach door to be locked, for example, the doors of an automobile. One of these units may be applied to each of the passenger doors and, if desired, to the baggage compartment door and to the hood. Each of the electro-magnetic units comprises a pair of solenoids which control a single soft iron bar that serves as a shear pin, which can be moved into locking position relative to the main lock bolt of the door to prevent such Ibolt being withdrawn from the door catch or into unlocking position to permit withdrawal of the bolt from the catch. One of the solenoids moves the bar to locking position while the other solenoidfmoves -it to unlocking position. The locking solenoids are connected in a locking circuit and the-unlocking solenoids are connected in an unlocking circuit, both of which are controlled by a master control switch located at a central control point readily accessible to the driver. This switch is preferably associated with the ignition switch of the car. Associated with the locking and unlocking circuits is a signalling circuit which signals, by causing a pilot light to ash, whenever the lockingior unlocking solenoids are energized and the bolt locking pins move properly into locking or unlocking positions. The system also includes an indicating vcircuit which is connected to all of the electro-magnetic units. This indicating circuitv includes a switch which is associated with the master switch and a `pilot light which will remain on constantly, after the switch of the indicating circuit is turned on, as long as the master switch is turned on and the locking system is functioning properly to maintain all of the doors locked. i

In addition to the master switch associated with the ignition key, Iprovide a key-operated switch on the exterior at each side of the car for actuating the unlocking circuit from the outside of the car. Either of these outside switches may Y be employed for gaining access to the car. Also,

I provide key-operated means on at least one of the units whereby it is possible to mechanically withdraw the shear pin from the locking bolt in case the electric systeml of the car fails.

The foregoingv and other. objects and advantages of the present invention will appear from the following'ldescriptionand appended claims when considered in connection with the accompanying drawings forming a part of the specification wherein like reference characters designate corresponding parts in the several views and wherein:

Figure 1 is a plan view of one of the electromagnetic units of my locking system.

Figure 2 is a side elevational view of the unit taken from the position indicated Iby line 2-2 of Figure 1.

Figure 3 is a vertical sectional view taken substantially along line 3-3 of Figure 2.

Figure .4 is a perspective view, partly broken away, of one of the units;

Figure 5 is a detail, in section, illustrating an electric grounding contact which is provided in the bolt.

Figure 6 is a similar view, but showing the grounding contact in a, different position.

Figure 7 is a diagram showing the circuit -of the system.

Figure 8 is a view of the face of the master'control switch of the system.

.Figure 9 is a view ottheinterior ora car illustrating diagrammatically how the system is .applied thereto.

Figure 10 is aperspective -yiewcf the unlocking switch opera/tedfrom the exterior .of the car.

Figure 11 is a plan vie'wof the unlocking switch.

With reference to the drawings, in Figures .1 to 4, I have illustrated the electro-magnetic un-it of my door vlocking System. One of these 4units will be associated witheacli door it isdesired vto control The bolt I of the door llockls mounted for reciprocation in the usuaimuner ion the hinged door 2 and is controlled in the `.usual way by handles connected v:to fthe lever mechanism `3.. When the door is closed. thenrQ-.iecting end of the bolt I eng-ages a keeper or 'catch .4 of the usual type `which is attached Ito the door jamie 5. as shown ybest in Figures 5 and .6..

I provide .the boltI with-a vertical bore .6 which is .adapted to receive -akertically reciprocable shear pin .1 to lock the-holt I in position, when desired, .citer the kholt engages the ica-tch II.l VThis shear pin 'I provides-the soft iron har `for a pair of superimposed vsolenoids B and B which are positioned directly above the bolt I. -asshown Vliest in Figures f2 and 3. As xviil be apparent hereinafter, the solenoid-8 .serves-as :the looking solenoid, while the solenoid -9 serves .as the unlocking solenoid. The solenoids :are attached by suitable brackets to a vertically disposed part Il) of .the door structure. In its ,lower 'or 'looking position, the pin I will extend :downwardly through the bore 5 `and lock the holt I .in locking position. In its upper or unlocking position, the-,lower rend of :the vshear tpin l will be withdrawn upwardly :from the here In order to aid :the .solenoids in :accurately loeating the shear pin inaeither docking or unlocking positions and lin order to hold it in either .of such positions. a .spring operated plunger I :I is provided, as .shown liest in Figures 2 .and 4. This plunger I I -is .mounted `for horizontal .sliding movementby means .of a pair of supporting .pins I2 which are carried hy the door and which extend into v4a. slot 'I3 formed in plunger .l I.l A leaf spring I4, anchored to :the door 'hy .member l5, has its opposite end :attached to the inner end of plunger II. `This spring .normally tends to vforce the plunger Ifl outwardly. The pin-nger carries on its outer .end a lsmall grooved .roller I6. `This roller ,is always Jheld .in embracing engagement with the side ofthe shear pin l hy means of the spring I4. The plunger extends between the two solenoids 8 and :9, as shown .best in Figure 2. The

pin 'I is reduced in diameter to form a locating recess I1, for cooperating with roller I6, and this recess will be located between the two solenoids when the shear pin 'I is in locking position. At a point spaced a substantial distance below the recess I'I is a similar recess I 8 formed by reducing the diameter of the pin 1. When the shear pin I is in its uppermost or unlocking position, the roller I6 will engage this recess I8 and maintain the pin in ysuch position.

In order to provide means for moving the pin 1 to unlocking position in case of power failure, I provide means for mechanically lifting the pin to withdraw it from the bolt I. This means comprises a cord or wire I9 which is connected to the upper `end vof the pin 'I. The upper end of this cord I9 is wound around and anchored to a rotatable pin 20 which is suitably mounted for rotation -on the door. The pin may be rotated from the outside by means of a key inserted into the lock 21| in which the pin ris mounted.' "1111s lock 2l is preferably of such ,a .type thatafter the pin has been rotated to lift the :shear 1 .so that the door may be opened, the keymust be rotated reversely to its original position before permitting removal of the key. Suhseqmantly.v movement of the pin 'I between locking :and unlocking positions will not be interfered with-by the cord I9.

In its lower position, the ,lower .end of pin :1 .engages the upper vend of a pin la, 4formed of insulating material, which :is suitably mounted for vertical sliding movement on va bracket 12 supported by the door :directly below `bolt 1I. This bracket 22 carries an insulating block 23 from which projects leaf springs 24 and 2.5.. The lower end of pin 1a eng-ages the upper spring 24 and insulating spacer 2 6 is provided between the spring contacts 24 and 25. The spring contacts 24 and 25 are adapted .to cooperate Awith coutact-s 21 and 28, respectively, ywhich are supported by an insulating block .29 that is .cm-Tied on the bracket 22. When pin .Z is in its lowermost position, it forces the spring contact-s 24 and 25 downwardly through :the medium of pin Ia. This causes contact v2e to breakaway from contact A21 and causes contact 25 to engage contact 2B. When the pin 1 is moved upwardly. contact 25 will :break away from contact 2B and contact 24 will engage contact 2.

When the pin I fis in its uppermostfposition, it engages an insulating pin 1b, shown in Fig ures 2, B and 4, that depends from Ia spring contact member 30. This member .2D is :carried by an insulating block 3l which is supported on a bracket 432. The :contact 30 .cooperates with a contact 33 which is carried lay ern-insulating bleek 34 whichis also attached :to -fbracket 32. Normally spring-.contact 30 is in'contact with contact `33.. However, when pin 1 moves upwardly and enga-ges :pin 1h, the spring 'oontact 30 is forced upwardly away from the -contact 33.

The boit I, :as shown in 'Figures 5 and 6, 'has la socket 35 termed within its outer end, An insulating sleeve 3'6 is .disposed Iwithin ythis socket and a pin 31 is reciprocably mounted in the sleeve. The outer .end -of the pini. carries Yan annular insulating member v38 which has `a recess withi-n its :outer yend which a contact "39 is disposed, .this contaetbeing connected elect-rlca'lly to pin 31. A `cormzrression spring 48 is disposed within the `outer end of socket and engages member 381:0 normally force this member and the pin .31 outwardly. A stop shoulder 4I is provided, for limited member 38, at the inner end of a throat 42 which communicates with socket 35. A ilexible pin or contact member 43 is adapted to en'- ter through `the throat 42 and to contact contact 39. This member 43 is carried by the door jambbehind the catch 4. As will later appear, contacts 39 and 43 function as grounding contacts. As shown in Figure 6, until Ithe door. reaches closed position with the bolt l behind catch Ll, the contacts 43 1and 39 will be separated. However, as illustrated in Figure 5, as soon as the bolt passes :the catch and moves behind it, the contact pin 43 enters the throat 42 and engages contact 39, moving member 38 inwardly slightly. Since contact 43 is slightly flexible and contact 39 is movably mounted, positive contact with these members will be insured each time the door is closed.

Associated with the electro-magnetic unit is, an unlocking switch 44. This switch is preferably made a part of a lock 2|a (Figure 1) similar to the lock 2l and must .be rotated by means of `a key which s inserted from the exterior of the door. The lock 2id is also preferably of such a type that it lrnust be returned to its original position before 4permitting removal of the key. The switch 44 includes an upper plate 45 and a lower plate 45 which are relatively rotatable. The upper plate 45 carries on its upper surface Ia conducting strip 45a and on its lower surface a pair of conducting strips 45b and 45e. The strip 45a is disposed almost at right angles to the strips 45h and 45e. Strip 45a is connect-l ed to :the contact points 45d provided yat its ends, while strip 45h is connected to the points 45e at its ends and strip 45e is connected to the points 45f at its ends. The upper surface of lower plate 419 carries a pair of spaced contact points 49d and a pair of points 4Gb. Normally the switch 44 is in inoperative position, as shown in Figure '1, with contact points 45e engaging points 46a and points 45j engaging points 45h. Points 45d, at the end of strip 45a, will be out of engagement with all the other pomts. When it is desired to operate the unlocking solenoids 9, the circuit may be crossed by rotating the switch 90 only from the position shown in Figure l1. This causeslpoints 45d to engagevone of the points 46a-and one of the points 4Gb. This will ac'tuate the unlocking solenoids, as will later appear. Switch 44 is then returnedto its original position by a reverse turn of the key through 90. ,Y

In Figure 8, I illustrate a dial which will be located at the central control point, for example, in Vassociation lwith the ignition lock 48 of the car. The dial 49 is 4provided with proper indications to show when the master control switch 59 is in locked, unlocked oroff positions and when the indicating circuit switch 5| isoff or on. The switch 50 is in the form of a ring which closely surrounds the ignition switch 48. Although no electrical connection is made between the ignition system and the locking electrical system, the juxtaposition of theignition key (also door unlocking key)\ with the door locking switch and the necessary procedure in locking the doors before exit is made from the car, greatly reduces the possibility of locking the keys within the car, as will be'more clearly app-arent hereinafter. The switch 5l is also in theform of a ring which closely surrounds ring 59 and is independently rotatable. .The dial 49 outward movement l of also carries a green pilot light G and |a redplot 6 light Rv; :As shown in r Figure 9, the master control Jswitch will be located adjacent the driver and each of the doors of the car will be provided with one of the electro-magnetic units. The locking mechanism 2l and associated pin lifting. cord I9 need be provided on only one of .the units. 4One of the switches 44, for unlocking the. door from the outside, is preferably provided at each side of the car. Although I illustrs/certa system for a two door carin Figures 7 and 9, it to be understood that the system carrbe ap-plied to any number of doors.

In' Figure 7, I illustrate how the electro-magnetic units are connected together electrically and incircuit with Ithe switches and the battery of the car. The battery 52 is provided with a ground 53 and with a positive lead 54 in which a'fuse .55 is incorporated. The line 54 is connected'. to a line 56 which leads to the main contact 51 ofthe switch 50. A shunt line 58 is connected to the -line 56 at opposite ends of a resistance.159 interposed in line 55. The line 53 has the pilot light R, connected therein in series. Connected to the power source in parallel are the locking and unlocking circuits which include the locking solenoids 8 and unlocking solenoids 9 and the lines `(il) and 6|. The locking circuit is illustrated bythe dash lines while the unlocking circuit is indicated by full lines. The movable contact of the switch 50 may be in either of the positions illustrated in Figure 7, the full line position being the unlocking position and the dash line position being the locking position. When in unlocking position, contact 51 of the switch is connected to contact 62 thereof. When in locking position, contact 51 is connected to contact 63.- Contact 63 is connected by wire 64 to line 60. Contact 62 is connected by wire 65 to line 6l. vEach end of the line 60 is connected to one of the .contacts 24 which is controlled by the lower end of pin 1. Each end of the line 6l is connected tolone of the contacts 39 which is controlled by the upperend of the pin 1. The points 45h of each switch 44 are connected in the line E9. The points 46a.of each switch 44 are connected in the line 6l. The locking solenoid 8 of each unit is connected by a line 6B to the contact 21. The unlockingsolenoid 9 of each unit is connected by' a line 61 to the contact 33. The contacts 43 are grounded, while the contacts 39, associated therewith, are connected in series to the locking and unlocking solenoids 8 and 9 of the respective units. IWires 13 and 14 provide this connection.

-The switch 5I controls the indicating circuit, a part lof which is formed by the line 56. This circuit includesthe ground wire 68 which is connected to contact 69 of switch 5I. The movable part of the switch 5| will be brought into position when the switch is on to connect contact 69 to contact 10. When the switch is oif these; contacts will be disconnected. A wire 1l leads from the contact 10 and is connected in seriesto the green pilot light G. One end of this wire 1l is connected to one of the contacts 25. Similarly, one end of the wire 56 is connected to the other contact 25. The contacts 28, ass ociated with contacts 25, are connected together by a wirev 12. ,Thus, the indicating circuit, which includes green light G, is connected in series to thelocking and unlocking solenoids.

The .circuit is in the condition illustrated in Figure?? 4with the switch 50 moved to the locking position and with the switch 5l on, when the passengers and driver are all inside the car and all-the doors-.have been locked. At this time,

f 254710, Ml.

7 the shear pins l will he down in locking position extending through the bolts l, The greenvpilot light will be on since the `circuit for it'wiil run from ground S8, through switch l.. through .wire 'H and light G, through theright Ahand contacts 25 and 28, wire 12, left hand contact-'urre 56 and .line 54 to battery i2; At this timcelec,

the locking circuit will he broken due tothe fact'.

that the contacts 24 and 21 have'beenseparatcd previously -loy downward movement of plus The red light R. w'ul not be on, dueto theafct" that its shunt circuit will not normally receive sulcient current to `light it, because. of the lirovision of the resistancei. However, thefcurrcnt whichreaches therlight G willbe sufcientto light y it. Although light R will normally. not besupplied with sumcient .current -to light it..` whenithe.

soienoids' orfll are energized, there will .the auchy a .drop in potential between the points where the. shunt line 58 is connected to line ,5.6. that sumcicnt current rwill be permitted to :flow :through 'the shunt line to light the red light R. The switches. The locking system. can he actuated to unlock the. doors only from thevcene.

trai control point at the drivers seat. Furthermore, .the doors .cannot be opened .fromzthe outside. If forsome reason, while the` car iis-'moving along, one of the shear pins 1 .accidcxrltallypliecomes withdrawn from the holt L'this willim mediately permit ythe contact 25 to move 'away from the eontactZB and break the circuitltothe green light .G at this point. This will:indicatey to the driver that the locking mechanism..is not functioning properly.

If it is now desired to unlock the rcar, :the switch 50 is turned to the unlocking position-.emunio Figure 7 Then current will flow from .therbattery 52 through line `54, line 56, through switch 5i, line 55, contacts 30, contacts, linesi'l. through unlocking solenoids 9, through .groundf'wlresflf andlcontacts 3.9 and .43 .to the grounding points; This will supply .thesolenoids .9 with current sume' cient to liftthe shear pins 1 to unlocking position: The red light R will be ones long 4as-curx'lentis supplied to the solenoids 9, since atthistimc suicient current will by-pa'ss throughline '5I to light the light. The circuit .to the iightR-will be from battery 52, throughlines ,lshunt'line 58, switch 50, line 55, line il, `contacts-1| .and 33, lines Alil, lines '13, and ground` contacts l! and 43. However, light R will loe on -cnlymomem tarily because when-the pins yl move upwardly, they engage -contacts to move them .away from contacts `33, breaking `the circuit ftorthe solenoids 9 and light R. At the same timc,-1the Y circuit to the light G is broken by upward move, ment of the contact 25 away from the `cox'ital'zts 28. The handles on the door of the car may now be turned to movethe-bolts l topermit opening of the door.

If it is desirednowv to lock the caralrom'fthe' outside, all the ydoors are closed with the exception of the one to be used bythey driver for-exit. Before leaving the car, the driver turns the switch back to locking position after he operates the door handle to pull the door bolt and separate contacts 39 andf43 of thatdoor. The switch 5l is preferably turned to ythe 05" posi.- tion so that theV green signal light willlnot function When the car is unoccupied. The circuit through 'the locking `rl-lecl'larllsrn 4of Athe -dOOlS which have already been closed lwillihavc*beer-1 completed at this time and the pins 1 thereof will be in locking position. Howevcr,therbolt ofthe particular door used Ior'exit 'will *notte supply vofy currentA will 8 locked x1-Position, duc to a .break in the circuit at the .'-contacts 39- and 43,` until alter it is slammed shut,pbut then Athe locking will take place-automatically. When this door is slammed shut, the contactsv 3.9 and 43 of .the locking mechanlsm .for that door are automatically engaged. When the contacts 39 and 43 are engaged, the cizcuitta 'the .locking snlenoids y8 is completed from battery 152, through lines 54, 5S, switch 5.0, line 4, line Si. contacts 24, contacts 2l, lines 66. lines uplincs 1.3 and .contacts 39 and 43 to the grounding points. At this time, contacts 24 are in their upper position v.in engagement with contacts'iz' However, yas soon as the solenolds 8 are the plus l are pulled. downwardly and force the-.contacts awayyfrom contacts 21, brefnkingthe circuit at these points.v Thus, the loekingsolenoidswill be only momentarily supplied with current. However, this momentary `also ashthe red light R forxaninstant untilthe .circuit is broken. The circuitA for .the light-R will be from the battery 5f through lines 54, shunt line 58, switch 50, line ,"line 80, contacts 24 vand 2T,.lines 56, lines 14 yand '14' -and grounding contacts 39` and 43. Al-

though the contacts 25 and A28 willbe in engagement, .the green light G' will not light, due to the 4fact thatV its circuit is broken by the switch 5t. Howeven-'the driver will see the red light ilashwhen he slams his door and this will indicate 'that the shear pin of the locking mechanism on his 'door moved into locking position. The light?. will go on* as soon ras locking solenoids 8 are -deenergized byseparation of contacts 24 and 2.

'When it is vdesiredto gain access to the car, one of the switches 44 may be actuated to cause the` points dat the end of strip 45a to engage one'of the points 48a and one of the points 4Gb. All other conta'ctpointsof the switch will be disengaged- This crosses-the lines B0 and vEl which will .cause a `circuit to be completed to the unlocking 'solencids 9 from the battery 52, through lines 54.456,'switch50, which will be in locking position, line 54, line 60,points 4Gb and 45d, strip switch 50 =is kept in locking position and the switch .5l is turned on. If all the doors are closed, they will belocked automatically and the driver need not lock each door individually or check each'door to sce that it is locked. This can -be determined by the driver at a glance at the `green pllotllght. As long as the driver desires to keep the doors locked they can only be opened fromthe central point at his seat. None of `the bolts of the 'door locks can be locked until that particular door is closed completing the circull: at the contacts y39 and. The green light .will be on when all :of the doors are :closed and will stay onas long as the pins l are in locking position. The red light will flash each time the locking solenoicls 8 or the unlocking solenoids 8 are energized. A miuinrum amount of current is 'used due to the fact that the solenolds are only momentarily energized, `the red light is only on momentarily and the green light requires little It will be apparentzthat I have provided a locking system having a `number of advantages. A number of advantages have been referred to in the description and others will be apparent.

Having thus described my invention, what I claim is:

1. A door locking system comprising electromagnetic units on each door to be controlled, a locking unit on each door controlled by the electromagnetic unit on such door, all of said electro-magnetic units being connected in a main circuit, a control switch for said circuit, and Vmeans for indicating each time said electro-magnetic units are energized, said means comprising a shunt circuit connected to the main circuit and including a signal, and a resistance element connected in said main circuit between the points where the shunt circuit is connected thereto so that the shunt circuit will receive sufficient current to actuate the signal only when said circuits are energized.

2. A door lockingsystem comprising electromagnetic units on each door to be controlled, a locking unit on each door controlled by the electro-magnetic unit on such door, each of said electro-magnetic units comprising a locking solenoid and an unlocking solenoid, a locking circuit and an unlocking circuit connecting the respective solenoids in parallel, a main control switch for controlling said circuits, and an additional switch interposed in bothcircuits between said main control Y,switch and one of said electromagneticunits and having conducting elements normally forming parts of said circuits, said additional switch being operable to move said elements into position to break said normal locking and unlocking circuits and having an additional conducting element which will connect said unlocking circuit to said locking circuit when said second switch is operated to break said normal circuits so that the circuit to said locking solenoid of each unit will be broken and the circuit to said unlocking solenoid of such unit will be made.

3. A door locking system comprising electromagnetic units on each door to be controlled, each oi said units comprising a locking solenoid and an unlocking solenoid, a locking circuit and an unlocking circuit connecting the respective solenoids in parallel, a main control switch for controlling said circuits, a power line connected to said control switch, each of the doors being provided with a bolt and a keeper, a locking pin associated with each bolt and movable into and out of a socket provided therein, said locking and unlocking solenoids of each unit being co-axially disposed directly adjacent each of said bolts and said locking pin extending therewithin and being movable in opposite directions by the respective solenoids, and contacts associated with the bolt and so arranged as to engage each other only when the bolt is in association with the keeper, said contacts being connected in circuit with said locking and unlocking solenoids, said locking circuit being provided with a pair of contacts which will be separated by movement of the locking pin to locking position and said unlocking circuit being provided with a pair of contacts which will be separated by movement of the locking pin to unlocking position.

4. A locking system according to claim 3 wherein said power line has a shunt circuit connected thereto and including a pilot light and a resistance element connected in said power line between the points where the shunt circuit is connected thereto.

5. A system according to claim 3 wherein a signalling circuit is connected in series to movable contacts associated with each of said units, said contacts being engageable by movement of the locking pin into locking position, and a control switch for said signallingv circuit associated with the main control switch.

6. A locking system according to claim 3 wherein said power line has a shunt circuit connected thereto and including apilot light, a resistance element connected in said power line between the points where the shunt circuit isfconnected thereto, and a signalling circuit connected in series to movable contacts associated with each of said units, said conta-cts being engageable by movement of the locking pin into locking position, and a control switch for said signalling circuit associated with the main control switch.

7. A locking system according to claim 3 wherein an additional switch is interposed in both locking and unlocking f circuits between said main control switch and one ofsaid units and has conducting elements normally forming parts of said circuits, said additional switch being operable to move said elements into position vto break said normal locking and unlocking circuits and having an radditional conducting element which will connect said unlocking circuit to said locking circuit when said second switch is operated to break said normal circuit so that the circuit so said locking solenoid .of ,such unit willbe broken and the circuit to said unlocking solenoid .of such unit will'be made.

8. fA locking system according to claim 3 wherein said power line has a shunt circuit connected thereto and including a pilot light, a resistance element connected in said power line between the points where the shunt circuit is connected thereto, a signalling circuit connected in series to movable contacts associated with each of said units, said contacts being engageable by movement of the locking pin into locking position, a control switch for said signalling .circuit associated with the main control switch, and an additional switch interposed in both locking and unlocking circuits between said main control switch and one of said units and having conducting elements normally forming parts of said circuits, said additional switch being operable to move said elements into position to break said normal locking and unlocking circuits and having an additional conducting element which will connect said unlocking cir-cuit to said locking circuit when said seco-nd switch is operated to break said normal circuits so the circuit to said locking solenoid of such unit will be broken and the circuit to said unlocking solenoid of such unit will be made.

y9. A door locking system comprising electromagnetic units on each door to be controlled, all of said units being connected in a main electric circuit, a control switch for said circuit, each of the doors being provided with a bolt and a keeper, a locking pin associated with each bolt and controlled by one of said units for engaging the bolt and positively securing it in locking position, contacts associated with the bolt and keeper and so arranged as to engage each other only when the bolt is in association with the keeper, said contacts being connected in and controlling the circuit to said units so that the locking pin cannot be actuated to engage the bolt as long as the door is opened, and a signalling circuit associated with said units, said circuit including movable contacts controlled by movement of said locking `ll pin immandoutl 'of locking position relative to the bolt.

10'; A door locking system comprising electromagnetic units on each doorto be controlled, all of said units being connected in a. main electric circuit, a control switcnfor said circuit, each of the doors being provided with ebelt and a. keeper, a locking pin f associated with each bolt and controlled by one of said* units for engaging the bolt and positively securing it in locking position, contacts associated withthe bolt and keeper and so arranged as tol engage each other only when the bolt isin aissoozziationy with the keeper, said contacts being connected in and controlling the circuit tosaid units so that the locking pin cannot be actuated to engage the bolt as long as the door is opened, a shunt circuit connected to said main circuit and including a. signal, and a resistance element connected. in said main circuit between the pointswhere the shunt circuit is connected'thereto sothat the shunt circuit will receive sirilcientV current to actuate the signal only when saidlocking or' unlocking solenoids are energized.

l1. A door'iocking system comprising electromagnetic units` on ecclrrdoor to be controlled, al1 of said units lacingv connectedy in a main electric circuit, ay control switch for said circuit, each of the'. doors being provided with a bolt and a keeper, alocking pin associated with each bolt and controlledbrone of said units for engaging the boltA and.; positively securing' it in locking position, contactsv associated with the bolt and keeper and sof arranged as to engage eac-h other only whenthe bolt iszin association with the keeper, said contacts being connected in and controlling 'they circuit to said units so that the locking pin cannot be actuated to engage the bolt as long as the door is opened, a signalling circuit associated with saidzunits, said circuit including movable contacts controlied by movement of said locking pin Vinto and out of locking position relative to the bolt and' e, main switch for controlling thezsignaliing'circuit, a shunt circuit connected in Vsaid mancircuit and including a signal, and a resistance element connected in said main circuit between tixepoints where the shunt circuit is connected thereto so that the shunt circuit will recetve'suiiicient current to actuate the signal-only when said locking or unlocking solenoids are energized.

FRANCIS E.v SEAMAN.

REFERENCES CITED The ioliowing references arel of record in the le of this patent:

UNITED SlAIESv PATENTS Number Name Date 956,580 Howard ..-...i fMay 3, 1910 2,031,523- Braueny --Fbl 18', 1936 2,061,978 P'entka, Nov. 24, 1936 2,156,387 Gcidnger yMay 2, 1939 2,184,350 Lakri Dec. 26, 1939 2,199,471 Vacca yMa/t 7', 1940 Certificate of Correction Patent No. 2,470,581 Mey 17, 1949 FRANCS E. SEAMAN It '1s hereby certified that error appears in the printed specification of the above numbered patent requiring correction es follows:

Column 10, line 30, for the Words circuit so that the circuit so read circuits so that the circuit to;

and that the seid Letters Patent should be reed with this correction therein that the Same may conform to the record of the case in the Patent Ofce.

Signed and sealed this 10th day of J anuery, A. D. 1950.

THOMAS F. MURPHY,

Assistant Ucmmzssoner of Patents. 

